JP2004-331011A discloses therein a wheel position identifying apparatus for a vehicle. The wheel position identifying apparatus includes acceleration sensors and wheel speed sensors. The acceleration sensors are arranged at locations for front-left, front-right, rear-left and rear-right tires, respectively. The wheel speed sensors are mounted on the vehicle body corresponding to the locations for the front-left, the front-right, the rear-left and the rear-right tires, respectively. Each acceleration sensor acts as a rotation state sensor and is referred to as a rotation state sensor hereinbelow. The wheel position identifying apparatus compares accelerations a1[i]-a5[i], which are detected by the acceleration sensors in the tires, with accelerations C1-C4 calculated based upon wheel speeds detected at the vehicle body side. A tire, which is associated with the wheel speed sensor at the vehicle body side, is specified based upon the acceleration level correlated between the tire side and the vehicle body side. Therefore, even when the tires are rotated, i.e., even when the positions of the tires are changed, a computer can identify the position of a particular sensor sending a particular signal. A conventionally known sensor may be applicable as the wheel speed sensor at the vehicle body side, for example a known sensor which is structured with a magnetic sensor in conjunction with a toothed rotor.
The aforementioned wheel speed sensor, which each is mounted at the vehicle body side, is structured such that noise affects precision in detecting a wheel speed while the vehicle is running at a low speed. Therefore, comparison of two types of accelerations and deriving of a correlation therebetween are time-consuming.
A need thus exists for a wheel position identifying apparatus for a vehicle, which identify positions of wheels in a short period of time and with reliability by use of a detection result of a rotation state sensor at a tire side (wheel side) and not by use of a detection result of a wheel speed sensor at a vehicle body side.